Open-end spinning frames of this type are known and typically have at each spinning station a spinning rotor supported on a supporting disk seat for rotation in a rotor housing on which a vacuum is applied. Each spinning station includes a pivoted cover on which is disposed a sliver opening device having a rotating opening cylinder for delivering opened fibers into the rotor and a fiber conduit plate for closing the front of the rotor housing. Each spinning station has a debris discharge opening in the pivoted rotor housing cover which communicates with a debris disposal arrangement extending along the spinning frame.
One such representative spinning frame is described, for example, in the manual "AUTOCORO" of the W. Schlafhorst AG & Co. As shown on page 1.3.20, an endless moving debris conveying belt extends the length of the machine underneath the sliver opening devices of the spinning units of the rotor spinning frame for receiving debris discharged through the debris discharge openings of the pivoted rotor housing covers and for conveying such debris to transfer stations disposed at the end of the machine, into which the belts are emptied.
Alternatively, it is also known to provide pneumatic debris aspirating devices in the area of the sliver opening devices in place of such mechanical debris disposal arrangements. For example, German Patent Publication DE 21 12 170 A1 describes a rotor spinning device in which a sliver fed between a draw-in roller and a feed trough is opened into individual fibers by means of an opening cylinder. In the course of this process, debris particles and fibers are also separated to the greatest extent possible. The opening cylinder conveys both components over a fiber guide surface into the area of a debris outlet opening. In the course of this conveyance, the fibers as well as the debris particles are accelerated by the opening cylinder or by the air flow circulating along with opening cylinder to approximately the circumferential speed of the opening cylinder. In the process, the fibers and debris particles have a tendency to leave the circular path tangentially as soon as the compulsory mechanical guidance is interrupted, such as takes place in the area of the debris outlet opening of the opening cylinder housing.
A debris collection chamber is disposed immediately below the debris outlet opening and is connected to a central aspirating device of the spinning frame through a connecting conduit.
A comparable open-end spinning device, slightly modified in the area of the debris outlet opening, is described in German Patent Publication DE 28 56 028 C2. In this case, the debris outlet opening is also designed as an aspirating opening for an air flow directed into the opening cylinder housing to prevent spinnable fibers from being released from the opening cylinder along with debris particles. This air flow is directed onto the opening cylinder to act in the nature of a pneumatic guide to keep the opened fibers on the opening cylinder as a result of their relatively large specific surface in relation to their low mass. However, the debris particles, because of their size and mass, have a clearly higher kinetic energy which overcomes this air flow, causing the debris particles to be propelled away tangentially. Subsequently, the debris particles are entrained by a further air flow and are removed through an aspirating opening. A debris chamber is disposed directly adjoining the debris outlet opening of the opening cylinder housing, which is divided into a debris separating zone and a debris removal zone by means of an air guide wall disposed at a short distance from the debris outlet opening.
Another open-end rotor spinning device with a debris chamber disposed underneath the opening cylinder is known from German Patent Publication DE 43 10 810 A1, which has two separate air flow systems with their own respective aspirating openings. An air flow system acting in the bottom area of the debris chamber disposes of the debris particles combed out by the opening cylinder, while a second, oppositely acting air flow system terminates in a suction flow rotating along with the opening cylinder. The particular disposition of the aspirating opening results in an essentially definite separation of the two flow systems.
Furthermore, the later published German Patent Publication DE 43 34 483 describes an open-end spinning device which has an opening cylinder housing disposed in the pivoted cover element of the spinning unit to be pivotable along with the cover element. The opening cylinder housing has a debris outlet opening with an associated pneumatically chargeable debris reception element disposed at a spacing opposite the opening, resulting in a free space between the debris outlet opening and the debris reception element which communicates with the ambient air. The debris reception element is releasably fastened on the cover element seated on a pivot shaft and is tilted downward around the pivot shaft together with the cover element when the spinning device is opened.
Debris removal at the opening cylinder housings of a rotor spinning frame represents an important element in achieving the objective of faultless processing of fiber materials. Even though the technology of the debris removal devices appears to be relatively simple, these devices are nevertheless very difficult and react sensitively to changes. Even small modifications in the area of the debris outlet openings can disadvantageously change the flow conditions and thereby have a considerable effect on the spinning result which can be achieved.